writer：Xiao J., Tan J., Jiang R., et al.
keywords：Drug-Delivery, Biomedical Applications, Sensing Applications, Nca Polymerization, Oxidative Stress, Coil Transition, Glutamic-Acid, Polypeptide, Polymers, Nanoparticles
source：期刊
Issue time：2018年
A homopolypeptide, namely poly(S-(2-carboxylethyl)-L-cysteine) (PCELC), with pH and redox dual responsiveness was prepared by ring-opening polymerization of S-(2-(methoxycarbonyl) ethyl)-L-cysteine based N-carboxyanhydride (MCELC-NCA) and subsequent hydrolysis. The pH-induced solution phase transition of PCELC was at pH = similar to 4.50 as revealed by DLS and UV-vis spectroscopy. The thioether linkages of PCELC can be readily oxidized by H2O2 at 40 degrees C yielding PCELCox with sulfoxide and sulfone linkages as revealed by H-1 NMR and FTIR. PCELCox also showed pH responsiveness with the variation of polymer aggregation sizes, but without solution phase separation. PCELCox can be partially reduced by 3-mercaptopropionic acid as suggested by H-1 NMR and FTIR analysis. The pH-induced solution phase transition behavior of the reduction product (i.e., PCELCre) was different from that of the as-prepared PCELC. Moreover, PCELC can be used as a pH and oxidation dual responsive stabilizer to control the aggregation of single-walled carbon nanotubes (SWCNTs) in aqueous solution.